Communication between neuron and target cell goes beyond the membrane permeability changes induced by neurotransmitters. Understanding the nature of these transynaptic signals and the molecular responses available to the target cell is important in formulating theories about the workings of the brain. A favorable model system for experimental investigation of this problem is developed in this project. Autonomic nerves modulate the development and differentiation of the parotid gland in the rat. The advantages of this preparation are that innervation occurs during the neonatal period and is accessible to manipulation; the target is fairly homogenous and is also differentiating during this time. We will study the neuronal modulation of development in terms of specific differentiated markers of parotid acinar cells: alpha-adrenergic, beta-adrenergic and muscarinic receptors, hormonally-sensitive adenylate cyclase, and neurotransmitter-induced secretion of K ion and alpha-amylase. The time course of synaptogenesis will be followed by biochemical and histochemical techniques. Subsequently we will examine the effect of early parasympathetic or sympathetic denervation on development of these differentiated biochemical and physiological properties. In describing the normal developmental course, we will learn whether different neurotransmitter receptors are introduced into the membrane in coordinate fashion or whether they are independently controlled. We will also determine whether the transmitter receptors are immediately functional or must await the maturation of other components. These questions relate directly to the mechanisms for neurotransmitter receptor maturation in the CNS.